But that wasn't always their main role. President Abraham Lincoln created the United States Secret Service (USSS) to deal with the mad influx of counterfeit money after the Civil War. A move ironically made just hours before he was assassinated April 14,1865. Four months later the Service was fully operational.

In the 2004 run up to the presidential election George W. Bush spoke at Louisiana State University (LSU), where National Geographic took a closer look at the Secret Service for a documentary titled "Inside the US Secret Service." The film follows the president's advance team as it works with local law enforcement making sure every threat is addressed before the president arrives.

National Geographic doesn't spill all the secrets, but what they let us in on is pretty cool.